ORDER DIPTERA: THE BRACHYCERA 141 



family have some resemblance to small robber-flies, but the 

 labella are fleshy (not pointed and chitinous), the legs are 

 not so stout, and the crown of the head is not deeply notched 

 between the eyes. They are predaceous and prey chiefly on 

 other flies. 



Family Empidid^ (e^7r/? = a gnat). Usually dull-coloured 

 flies of small size. The wing - venation is very variable, 

 the 3rd and 4th longitudinal veins may be forked, and 

 the anal cell may be large, or the venation may be as 

 simple as that of a house-fly ; sometimes there is no discal 

 cell. Head spherical, eyes usually large. Antennae of 2 or 

 3 segments, with or without a terminal style or a bristle 

 which is usually terminal but may be dorsal. No fringe of 

 bristles on the edge of the mouth. Proboscis short or long, 

 usually rigid and formed for piercing. Thorax sometimes 

 very convex. Legs usually slender ; some of the segments 

 may have a regular comb of spines, something like the 

 raptorial legs of a Mantis. The family is a large one, and 

 the species are predatory on other flies. 



Family Dolichopodid^. (Fig- 46) (&X(xo'? = long ; '""oJ? 

 = foot). Usually brightly metallic (often bright green) flies. 



Fig. 46.— Dolichopodid Fly. 



with long, slender legs. The wing venation is as simple as, 

 or simpler than, that of a house-fly ; the anterior cross- vein 

 lies near the root of the wing ; the anterior basal cross-vein 

 is absent, so that the discal and 2nd basal cells are confluent ; 



